Maybe this is well known, but I just discovered it and it gave me great joy. By adding !hoogle, !hayoo, or !hackage to any query, duckduckgo.com automatically searches in the respective search engine for you.

If you use Chrome, you can add a search engine so that you can use the URL bar. For Hoogle, just set the keyword to 'hoogle' and the URL to http://www.haskell.org/hoogle/?hoogle=%s. Then you can type hoogle, hit tab, and enter what you want to search.

Oh the ability to set different search engines has definitely existed for a while. What's new is that it's integrated into the "magic bar" thing so you can just type "hoog"+tab, without having to choose from a drop-down or anything like that. I have something similar set up for Reddit so that it goes to a subreddit instead of searching.

On the other hand, maybe they did have that and I was just that tech-unsavvy.

No, they did have it, with %s and all. You go to the bookmark manager, add the search engine you want with that %s URL as the URL, and set the keyword to whatever (in this case "hoog"); then typing "hoog aoeu" in the location bar would go to http://www.haskell.org/hoogle/?hoogle=aoeu . This worked back when the location bar was still just a simple combo box, not the fancy thing it is today.